Also a standout athlete, Austin was on the school's track & field team, where he was a top competitor in the sprinting, jumping and throwing events. He recorded the third-longest javelin throw in Bergen County history, with a throw of 65.44 meters. He placed third in the triple jump event at the 2001 New Jersey Meet of Champions, with a leap of 13.35 meters. He got a personal-best leap of 6.81 meters in the long jump. In sprints, he had career-best times of 10.8 seconds in the 100 meters and 22.28 seconds in the 200 meters.[4]

Austin rushed 15 times for 140 yards and one touchdown.[5] In 2003, Austin set a Monmouth single-season record for touchdown catches with 12.[5] He ran 4.47 second 40-yard dash and jumped 40.5 inches in the vertical leap at the 2006 NFL combine.[6][7]

Austin was signed as an undrafted free agent in 2006 by the Dallas Cowboys. He made the team based on his potential and was used mainly on special teams, returning 29 kickoffs for 753 yards and recorded 5 tackles.[8] His main highlight of the year was in the Cowboys playoff game against the Seattle Seahawks. He returned 3 kickoffs for 136 yards in the game, including a 93-yard touchdown return. In the 55 postseason games in franchise history, it was the Cowboys' first ever kickoff return touchdown.

Austin was the team's main kickoff returner, ranking third in the NFC and ninth in the league with a 25.5 average on 24 attempts for 612 yards. He set career-highs with six kickoff returns for 166 yards against the Green Bay Packers. He also recorded his first career reception against the New York Jets.

Austin had a strong training camp and was contending for the starting position that was open with the departure of Terry Glenn, until spraining his knee in the third preseason game against the Houston Texans. After missing some games with the injury, he exploded against the Green Bay Packers registering 115 yards on two catches for his first career 100-yard game and first touchdown. He suffered a second knee injury against the Washington Redskins and missed three games.

With the release of Terrell Owens, Austin started the regular season as the Cowboys' No. 3 receiver. During free agency, the New York Jets looked at Austin but did not offer him a contract, possibly because they would have had to give the Cowboys a second-round draft pick in order to sign him.[9] Before the year, Football Outsiders rated Austin as the top prospect in football on their Top 25 Prospects list.[10]

Austin got his first NFL start on October 11, 2009 against the Kansas City Chiefs, as a replacement for injured Roy Williams. Austin had 10 catches for 250 yards (a Cowboys record for receiving yards in a single game, breaking Bob Hayes' 246-yard effort in 1966 against the Washington Redskins) and 2 touchdowns including the 60-yard game winner in overtime. Austin made his second career start on October 25 against the Atlanta Falcons replacing Patrick Crayton as the No. 2 receiver. Austin solidified his place as a starting receiver with 171 receiving yards along with 2 touchdowns. After only two weeks as a starting wide receiver, Austin was the ninth-most productive receiver in the league going into Week 8, and moved up to eighth just four weeks later having caught his 8th touchdown against the Oakland Raiders on Thanksgiving Day. Against the Giants in week 13 he had 10 catches for 104 yards and a touchdown.[11]

December 29, 2009, Austin was selected to the 2010 Pro Bowl, his first. He went on to lead the NFC (third overall in the NFL) with 1320 receiving yards for the 2009 season. He also tied for first in the NFC with 11 receiving touchdowns which was tied for third in the NFL for receiving touchdowns in only starting 11 games in the 2009 season.

On September 9, 2010, Austin agreed to a six-year contract extension that began in 2011. The deal included $17 million in guaranteed salary. He signed a $3.168 million contract in June 2010 and his extension was worth $54 million, which brought the total value of his contract to $57 million.[12] The team paid a very high first year salary ($17 million), by taking advantage that the NFL collective bargaining agreement wasn't renewed, and in the final year of the agreement there was no salary cap system in place. Even though the NFL initially approved the contract, in 2013 commissioner Roger Goodell would penalize the Cowboys by taking $10 million from the team's original $120.6 million salary cap space.[13]

With 10 catches in each of the first two games of the 2010 season, Austin became the second player in Cowboys history to record double-digit catches in consecutive weeks.[14] On Thanksgiving Day, Austin scored a 60-yard touchdown on an end-around. However, the Cowboys lost 30-27 to the New Orleans Saints.

He finished the season with 69 catches for 1,041 yards and 7 touchdowns. He made his second consecutive Pro Bowl in 2010, replacing DeSean Jackson who sprained his MCL during practice for the Pro Bowl.[15]

Austin's 2011 season started well with a 5-catch, 90-yard performance in week 1, followed by a career-best mark for touchdowns in a game with 3 to go along with 9 catches for 143 yards in a week 2 victory over the San Francisco 49ers.

In week 14 while playing against the New York Giants to secure the division title and a playoff spot, he lost in the lights of Cowboys Stadium a first down pass from Tony Romo that would have won the game for the Cowboys, who ended losing 34-37 and eventually missing the playoffs.[16]

Austin's 2011 season was marred by nagging hamstring injuries which caused him to miss 6 games and limited him to his lowest reception, touchdown, and yardage output since the 2008 season.

After having a disappointing season, Austin started 2012 with 4 receptions for 73 yards while also grabbing a key touchdown in the 4th quarter of a 24-17 upset win over the Super Bowl defending champions New York Giants. The next game was a surprise defeat to the Seattle Seahawks, where he had 5 receptions for 63 yards while also grabbing a touchdown. The next week, in a victory over the Tampa Bay Buccaneers, Austin had 5 receptions for 107 yards. In the fourth game against the Chicago Bears, he had 4 receptions for 57 yards while also grabbing a touchdown in a losing effort caused by the Cowboys' 5 interceptions. He bounced back with 5 receptions for 97 yards with a touchdown in a victory over the Carolina Panthers. In a Week 13 win over the Philadelphia Eagles, he had 2 receptions for 46 yards with a touchdown. Austin's multiple injuries and the emergence of Dez Bryant as the Cowboys' leading wide receiver, hurt his chances of reaching 1,000 yards, but still had a productive year with 943 receiving yards, 66 receptions and 6 touchdowns.

Austin looked to bounce back in 2013. After a Week 1 performance with 10 receptions and 72 receiving yards in a victory over the New York Giants, in the next two weeks, he would be held to 5 receptions and 53 receiving yards, while suffering a hamstring injury in the third game. After being shut down by the team in an effort to return him to health, he did not have another reception until a Week 12 victory over the New York Giants. In that game, Austin had one reception for 17 yards followed by another discouraging performance in a Thanksgiving victory over the Oakland Raiders, with one reception for 18 yards. His season would end up being a disappointment after missing five games with a left hamstring injury, never displaying his explosive speed and being held without a reception in two games. Austin finished with his lowest receiving numbers since his second year in the league and his future with the team at risk, taking into account his history of hamstring injuries and rookie Terrance Williams playing well in his absence.

On March 11, 2014, it was announced that Austin had been designated as a post-June 1 release, ending his tenure as a Dallas Cowboy.[17]

On March 31, 2015, Austin and the Philadelphia Eagles agreed to terms on a one-year deal worth $2.3 million.[19] Austin, who was projected to have a big role in a young and inexperienced wide receiver corps, was held to 13 catches for 224 yards and 1 TD in 11 games. He had some moments, such as a 39-yard catch and run for a TD against the Redskins, but he was still criticized for not producing, as he was held to 0 catches in 5 different games, with a season high of 4 catches for 52 yards. On December 7, 2015, Austin was released.[20]

In 2011, Austin founded The Austin Family Foundation with help from his family. The Austin Family Foundation's mission is to support and promote youth programming, in lower income areas, that focuses on character development and community involvement.